The following commit has been merged into the locking/core branch of tip:

Commit-ID:     7b125c44d0b7f617ee81dffd14ce116149d03cb6
Gitweb:        https://git.kernel.org/tip/7b125c44d0b7f617ee81dffd14ce116149d03cb6
Author:        Thomas Gleixner <tglx@kernel.org>
AuthorDate:    Tue, 02 Jun 2026 11:09:47 +02:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 03 Jun 2026 11:38:50 +02:00

x86: Select ARCH_MEMORY_ORDER_TSO

The generic unsafe_atomic_store_release_user() implementation does:

    if (!IS_ENABLED(CONFIG_ARCH_MEMORY_ORDER_TSO))
        smp_mb();
    unsafe_put_user();

As x86 implements Total Store Order (TSO) which means stores imply release,
select ARCH_MEMORY_ORDER_TSO to avoid the unnecessary smp_mb().

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://patch.msgid.link/20260602090535.564499644@kernel.org
---
 arch/x86/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f3f7cb0..1ce62a9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -113,6 +113,7 @@ config X86
 	select ARCH_HAS_ZONE_DMA_SET if EXPERT
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_HAVE_EXTRA_ELF_NOTES
+	select ARCH_MEMORY_ORDER_TSO
 	select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE
 	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
 	select ARCH_MIGHT_HAVE_PC_PARPORT